The present invention relates to a device for connecting a fractured bone, more particularly within the femoral neck area, consisting of a bone fastening cover plate with fastening perforations that can be connected with the bone by means of a bolt connection and which extends parallel to the longitudinal axis of the bone, a sleeve positioned at an angle to the fastening cover plate for accommodating a bone screw or a bone pin and a trochanter supporting plate.
For the osteosynthesis of pertrochanteric fractures, i.e. for the stable retention of bone fragments in transverse or short oblique fractures it is known to take care of the fractures of the femoral neck by means of dynamic cover plate screws. Such cover plate screws consist of a bone screw which, from the trochanter, i.e. from the greater trochanter which is located laterally on the proximal femoral shaft, is driven or screwed into the proximal fragment and of a bone plate which is fixed to the distal fragment by means of screws. So-called Pohl's plate screws are employed here which consist of the bone plate and a sleeve formed onto the same at an angle for receiving the bone screw or a bone pin, while the bone plate is, by means of a bolt connection, attached to the same extending parallelly to the longitudinal axis of the bone and fitting snugly against the bone.
It is known furthermore to form onto the bone contact plate of such cover plate screws a trochanter supporting plate which projects cranially, thus in the direction of the head, over the actual fastening cover plate or bone contact plate and which has a configuration approximately adapted to the shape of the trochanter and which, subsequent to the cover plate screw being fastened to the bone, fits snugly against the trochanter and thus supports the trochanter. For it has been shown that when the femoral fracture extends into the trochanter or extends as far as underneath the trochanter, the otherwise so ideal technique developed for taking care of a fracture has reached the limits of its efficiency. That is why, in order to improve the efficiency of the cover plate screw in the case of such types of fractures, the known cover plate screws are provided with a trochanter supporting plate. However, it is essential that a cover plate screw provided with a trochanter supporting plate forms a one-piece implant, which presupposes that the surgeon has to have an extensive assortment at his disposal besides the already existing assortment of implants.
According to the DE-A-20 30 249, a device is known intended for surgical purposes for connecting a fractured bone, particularly within the area of the femoral neck which, with the aid of screws that engage into the latter, is connected with a splint, on which, at one of its extremities, a connecting member is disposed that is adjustable at an angle to the bone, which member is mounted on a mounting means constructed so as to have the form of a circular arc, which is rotatably and fixably arranged in a circular cap in the splint, whereby the possibility is provided of making use of differently constructed splints, each splint in this case being equipped solely on one of its ends with a circular cap in which the mounting means can be rotated. Due to the circumstance that the mounting means of the connecting member is secured to the splint, in many instances merely the additional mounting means and no specially constructed splint is required, which is always of advantage when, besides a femoral fracture, a fracture of the femoral neck supervenes which then calls for the employment of a connecting member, whereas, when it is a question of a fracture of the femur, only one splint is required, different forms of splints being made use of here depending on the size of the thigh and the type of the fracture in question. However, owing to the fact that the mounting means is rotatably attached to the splint and that the connection is effected by means of a bolt connection, the possibility cannot be excluded that the mounting means with the connecting member is twisted relative to the splint or that, already when applying and securing the entire device, a displacement of the mounting means relative to the splint takes place, as a consequence of which, in the case of a femoral neck fracture, the femoral neck is displaced within the area of the fracture surface relative to the femur. To this is further added the circumstance that no trochanter supporting surface exists at all. For the mounting means provided and secured to the splint, when the connection is mounted, does not rest against the trochanter, but projects from the trochanter surface while forming an interspace; nor is any provision made for shaping the mounting means so that the trochanter is embraced by section.
The EP-A-0 046 773 relates to a device for fixing the femoral neck and the greater trochanter on the shaft of the femur of a human being. This device is characterized by an angle plate whose leg, constructed as blade portion, is driven axially into the neck and who$e other leg constructed as shaft section is fixed on the shaft, as well as by a forked plate that is fastened to the shaft section of the angle plate and/or to the shaft and which fixes the trochanter on the neck. For the purpose of rotating the femoral neck about 90.degree. in order to remove the destroyed point on the femoral neck from the load area and so as to bring a non-destroyed point of the condyle into the load area, the blade portion of the device must be driven into the neck. If the femoral head has a plurality of fractured areas and if, for example, a substantial area of the greater trochanter is worn, in that case the driving in of the blade portion would lead to a further damaging of the femoral head. To this is added the circumstance that in numerous cases a driving in of parts into the femoral neck or into the femoral head is not possible at all, so that this device cannot be employed in all cases of femoral neck fractures This device is constructed in two pieces and consists of a forked plate and an angle plate, the forked plate in this case being displaceable on the shaft section of the angle plate in the longitudinal direction of the shaft; the shaft section of the angle plate and the forked plate have to be fastened to the shaft so as to lie on top of each other by means of screws. This device is constructed exclusively for a fixation of the femoral neck and of the greater trochanter on the shaft of a femur. One proceeds here from the assumption that the fixation becomes necessary for the healing process of a fracture which is e.g. of such a type of double fracture in which the greater trochanter has detached itself from the femoral neck and the femoral neck from the shaft, but also in other cases as, for instance, where the condyle is destroyed within its load area. In that case the femoral neck is separated from the shaft and from the greater trochanter and turned about 90.degree. in such a way that a healthy area of the condylus becomes the load area. It is for this reason that this fixation device has to be provided with a part, viz. the blade portion, which is driven into the neck in order to be able to twist the femoral neck after its separation from the greater trochanter.
A femoral neck implant with a femoral neck plate which, for its attachment to the outside of the femur is, along its longitudinal axis, provided with several reception apertures for cortical screws and which, on its upper area, is provided with a shaft to be implanted extending in an obtuse-angled manner in its longitudinal axis and reaching subtrochanterically as far as into the femoral neck and, possibly, into the femoral head, is known further from the DE-A-35 34 747. In this integrally constructed femora neck implant, its upper area forms a one-piece connected extension approximately adapted or adaptable to the outer contour of the greater trochanter which possesses one or several reception apertures for spongiosa screws to be fastened extending pertrochanterically as far as into the femoral neck or into the femoral head, while the shaft is constructed so as to be externally smooth and a and circularly cylindrical in shape and is, by means of an external thread at its end, detachably fastened in an internal thread recess within the upper area of the femoral neck plate.
It should be possible to use a femoral neck implant constructed in this way with a minor operative effort while maintaining the physiological femoral neck angle, and it should also permit subjecting it to a primary post-operative load in the case of unstable pertrochanieric fractures without the existence of a mechanical breakdown of the effected osteosynthesis. However, what is essentially involved in the case of this femoral neck implant is the fastening of a one-piece femoral neck plate with a formed-on plate-shaped section as trochanter supporting surface. Due to the one-piece construction of the femoral neck plate, no possibility of adaptation to the most widely varied anatomical conditions and no combinability with another implant assortment for pertrochanteric and subtrochanteric femoral fractures is possible.
The DE-A-10 46 827 describes a one-piece connecting device for juxta-artucular bone fractures, in which case said connecting device consists of a shaped member constructed in one piece which is provided with one section as bone fastening cover plate and one section as trochanter supporting surface. Within the area of the trochanter supporting plate, which is constructed so as to extend in the form of a circular arc, drilled holes or perforations for fitting screw pins, fastening screws and the like are provided, while the shaped member of the connecting device is provided with a screw or pin guide sleeve which has an internal thread into which an external thread engages that is constructed within the area of the screw head of the screw pin.
The hip pin according to the DE-A-18 13 807 consists of a shaft plate which is made to fit snugly along the lateral surface of the femoral shaft below the trochanter and which is equipped with a trochanter contact plate and which, furthermore, has a pin portion which is provided with a passage or axial bore that serves to accommodate a compression means which is characterized by an elongated shaft or stem which, on its outermost end, bears swivelable gripping members so that, when the hip pin is tightened, the femoral neck portion to be aligned in its fracture point is urged against the shaft plate fastened to the femur. This connecting device, too, is of one-piece construction.
The U.S. No. 2,443,363 describes a shaft plate for fastening on a femur, in which case the shaft plate consists of an approximately U-shaped sectional member and can, with the aid of an extensible or telescopic section, be varied in its length. Even if this shaft plate is constructed in two pieces, the two-piece construction solely serves the purpose of rendering a variation in length of the shaft plate possible. However, the shaft plate according to this U.S. publication does in no way consist of a bone fastening cover plate with a bone screw reception sleeve and the actual trochanter supporting plate with a perforation for passing through the bone screw reception sleeve of the bone fastening cover plate.
The present invention is based upon the technical problem of providing a device for connecting a fractured bone, more particularly within the area of the femoral neck and to thus provide a cover plate screw for the osteosynthesis of pertrochanteric fractures according to the type described in the beginning which, for the sake of achieving a greater degree of adaptability to anatomical conditions, renders possible an arbitrary combinability wit: a smaller assortment with the existing implant assortment of a manufacturer for pertrochanteric and subtrochanteric femoral fractures.